Current prediction in a switching power supply

ABSTRACT

A high efficiency switching power supply including an analog front end, a battery control circuitry portion, a display and equalization circuitry portion, field effect transistor (FET) drivers, an isolated power supply transformer circuitry (and three associated sets of tap circuitry), microcontroller circuitry, oscillator circuitry, overcharge protection circuitry, programmable logic circuitry portion, and a zero current predictor. Overbiasing of the FET power supply switches, and/or other various circuitry features disclosed herein, helps achieve electrical power efficiencies of preferably greater than 95%, even more preferably greater than 98% and even more preferably greater than 99%. Preferably, the switching power supply has one or more of the following: (1) high electrical power efficiency (&gt;95%. &gt;98%, &gt;99%); (2) overbiasing of a gate of a power supply switch; (3) a power supply switch with a low gate capacitance ratio; (4) multiple modes of operation; and (5) current prediction wherein an inductor voltage is used to control a constant current capacitor whose voltage indicates the level of current in the inductor.

RELATED APPLICATION DATA

This application claims any and all applicable benefits based on thefollowing provisional patent application(s): (1) U.S. patent applicationNo. 60/592,386 filed on 2 Aug. 2004; (1) U.S. patent application No.60/656,911 filed on 1 Mar. 2005; (2) U.S. patent application No.60/656,889 filed on 1 Mar. 2005; (3) U.S. patent application No.60/656,913 filed on 1 Mar. 2005; (4) U.S. patent application No.60/657,417 filed on 2 Mar. 2005; and (5) U.S. patent application No.60/656,914 filed on 1 Mar. 2005. All of the foregoing patent-relateddocuments are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to power supplies and more particularly tohigh efficiency dc-dc converter switching power supplies.

DESCRIPTION OF THE RELATED ART

Power supplies and switching power supplies are well known andconventional. A switching power supply generally includes: (1) an inputpower signal (see DEFINITIONS section for definition of “power signal”);(2) a power supply switch set; (3) a passive component set; (4) acontroller; and (5) an output power signal.

The power supply switch set includes at least one power supply switchthat can be turned on and off. A switching power supply will often havemore than one power supply switch in its switch set. Preferably, theswitch(es) is/are constructed as transistor(s), such as a field effecttransistor(s) (FET(s)). The passive component set is at least onepassive component, such as an inductor or capacitor. A switching powersupply will often have more than one passive component in its passivecomponent set. The power supply switch set and passive component set areelectrically interconnected so that when the power input signal flowsinto the interconnected circuitry of the power supply switch set andpassive components, the opening and closing of the power supplyswitch(es) effectively convert the input power signal into the outputpower signal having some predetermined electrical characteristics (e.g.,a regulated dc voltage).

In a switching power supply, the power supply switch(es) need to beactively controlled to open and close on an ongoing basis so that theoutput power signal will achieve and maintain its desired electricalcharacteristics. The controller exercises this control over the powersupply switches. The controller uses logic (e.g., a programmedmicrocontroller) to analyze control input signals and send controloutput signals out to open and close the power supply switch(es). Thecontrol input signals represent information (e.g., voltages, currentvalues) sensed at various portions of the switching power supplycircuitry. For example, the voltage of the power input signal may besent to the controller as one of the control input signals. If thevoltage of the power input signal drops for a little while, thecontroller would generate its control output signals to operate thepower supply switch set to compensate for voltage drop indicated by thepower input signal voltage control input signal. It is noted that thecontroller may be distributed in space and/or amongst separatecomponents.

U.S. published patent application publication number 2002/0017897(“Wilcox”) discloses a switching voltage regulator which is alleged toexhibit high efficiency over broad current ranges, including low outputcurrents. Wilcox further states that its disclosed control circuit canfacilitate over 90% efficiency in a 5-volt synchronous switchingregulator for an input voltage of approximately 10 volts. Wilcox furtherstates that efficiencies of over 95% can be maintained. The Wilcoxswitching regulator generates a control signal to turn switchingresistors off when voltage at the output can be effectively maintainedat the regulated voltage by the charge on an output capacitor.

U.S. Pat. No. 4,495,554 (“Simi”) discloses a switching power supplywherein the input elements, including the controller, are fully isolatedby a transformer. Simi explains the way in which its switching powersupply uses, the technique of overbiasing: “Thus, during each period inwhich controller 51 gates FET 9 on, transistor 19 is driven on.Transistor 19 is overbiased and can conduct any amount of current whichmight be provided by line 33. During the other periods, transistor 19 ispositively driven off. Diode 20 is then forward biased and provides ashunt to ground which protects transistor 19. As transistor 19 is turnedon, current flows through the primary of transformer 35, bypassing diode37 and resistor 39 since transistor 19 constitutes a direct path to theground reference potential.”

U.S. Pat. No. 6,348,784 (“Gofman”) discloses a switching power supplyincluding a series regulator circuit. The regulator circuit includes aMOSFET that operates with voltage biasing circuitry. The voltage biasingcircuitry offsets a voltage level between the gate and drain terminalsto reduce the difference in voltage between the drain and the sourceterminals associated with the gate-to-source threshold voltage. Thisbiasing thereby reduces the power dissipated within the series regulatorelement.

U.S. published patent application publication number 2004/0119448(“Wiegand”) discloses a controller apparatus that varies the amplitudeof an electrical power supply voltage. Wiegand states: “The controllerapparatus . . . may be used to implement all otherwise conventionalconverter types, buck, boost, and inverting (and duals of these) versionto obtain different regulating characteristics . . . ”

U.S. published patent application publication number 2004/0100807(“MacDonald”) discloses a dual input AC/DC power converter with dualprogrammable DC voltage outputs. The power converter includes anAC-to-DC converter, a DC-to-DC booster converter, and a DC-to-DC buckconverter. The two programmable DC output voltages may be generated as afunction of both AC and DC input voltages.

U.S. published patent application 2003/0214271 (“Bradley”) discloses asystem for bi-directional power conversion in a portable device with abattery, particularly wireless communications devices. Bradley states:“The invention . . . us[es] a single inductor to perform both buck andboost power conversion operations . . . thereby reducing the number ofcomponents . . . ”

U.S. Pat. No. 6,377,032 (“Andruzzi”) discloses an apparatus for virtualcurrent sensing in a DC-DC switched mode power supply. A programmablecurrent source charges a current sensing capacitor and the voltageacross the capacitor simulates the rising slope of the voltage across aconventional current sensing resistor. A ramp capacitor is charged by asecond programmable current source. The sum of the voltages across thecapacitors is used to discharge the current sensing capacitor tosimulate the falling slope of current across a conventional resistor.

U.S. Pat. 5,982,160 (“Walters”) discloses a DC-DC converter thatprovides sensing of the output current for regulation. The DC-DCconverter includes a power switch, an output inductor connected acrossthe power switch and a current sensor connected in parallel with theinductor. The current sensor includes a resistor and a capacitor,preferably with fast values.

Description Of the Related Art Section Disclaimer: To the extent thatspecific publications are discussed above in this Background section,these discussions should not be taken as an admission that the discussedpublications (e.g., patents) are prior art for patent law purposes. Forexample, some or all of the discussed publications may not besufficiently early in time, may not reflect subject matter developedearly enough in time and/or may not be sufficiently enabling so as toamount to prior art for patent law purposes.

SUMMARY OF THE INVENTION

The present invention relates to switching power supplies and circuitryportions of switching power supplies. Preferably, the switching powersupply has one or more of the following: (1) high electrical powerefficiency (>95%. >98%, >99%); (2) overbiasing of a gate of a powersupply switch; (3) a power supply switch with a low gate capacitanceratio; (4) multiple modes of operation; and (5) current predictionwherein an inductor voltage is used to control a constant currentcapacitor whose voltage indicates the level of current in the inductor.

Various embodiments of the present invention may exhibit one or more ofthe following objects, features and/or advantages:

(1) higher power efficiency switching power supply;

(2) more reliable switching power supply (e.g., reduces or eliminatesphantom switching);

(3) a switching power supply advantageous for use with rechargeableelectrochemical cells (e.g., lithium ion polymer batteries);

(4) a less expensive switching power supply;

(5) switching power supply with isolated reference voltages for poweringthe controller;

(6) power supply with both variable frequency and variable duty cycle;

(7) switching power supply including optical signals; and

(8) switching power supply wherein control signals driving the powersupply switch(es) and transmitted through a capacitive coupling.

According to one aspect of the present invention, a switching powersupply includes a power signal input, a power signal output, a passivecomponent set, an active component set, zero current predictorcircuitry. The power signal input is structured as circuitry forproviding an input electrical power signal to the switching powersupply. The power signal output is structured as circuitry for providingan output electrical power signal from the switching power supply. Thepassive component set includes at least one inductor and a capacitor.The active component set includes a first power supply switch connectedin series between the inductor and capacitor. The active component setis electrically interconnected to the passive component set so that aswitch position of the at least one power supply switch at leastpartially controls the flow of electrical power through the passivecomponent set. The zero current predictor circuitry structured andelectrically connected to predict when inductor current will fall tozero and to send a signal to close the first power supply switch basedon this prediction.

According to a further aspect of the present invention, a switchingpower supply includes a power signal input, a power signal output, apassive component set, an active component set, zero current predictorcircuitry. The power signal input is structured as circuitry forproviding an input electrical power signal to the switching powersupply. The power signal output is structured as circuitry for providingan output electrical power signal from the switching power supply. Thepassive component set includes at least one inductor and a capacitor.The active component set includes a first power supply switch connectedin series between the inductor and capacitor. The active component setis electrically interconnected to the passive component set so that aswitch position of the at least one power supply switch at leastpartially controls the flow of electrical power through the passivecomponent set. The zero current predictor circuitry structured andelectrically connected to predict when inductor current will fall tozero and to send a signal to close the first power supply switch basedon this prediction. The zero current predictor circuitry includes a zcpcapacitor electrically connected and controlled based on the voltageacross the inductor so that the zcp capacitor's voltage proportionallymirrors the inductor current.

In some further aspects, the zero current predictor circuitry includes azcp capacitor, a zcp integrator and a zcp comparator. The zcp capacitoris electrically connected and controlled based on the voltage across theinductor so that the zcp capacitor's voltage proportionally mirrors theinductor current. The zcp integrator integrates the rate of change ofzcp capacitor voltage to determine zcp capacitor voltage. The zcpcomparator signals on the condition that the zcp voltage determined bythe integrator has fallen below a minimum threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 a is an analog front end first portion of a first embodiment of aswitching power supply;

FIG. 1 b is an analog front end second portion of the first embodimentpower supply;

FIG. 2 is a capacitor set for use in the first embodiment power supply;

FIG. 3 a is a battery control first portion of the first embodimentpower supply;

FIG. 3 b is a battery control second portion of the first embodimentpower supply;

FIG. 4 is a display and equalization first portion of the firstembodiment power supply;

FIG. 5 is a capacitor set for use in the first embodiment power supply;

FIG. 6 is a display and equalization second portion of the firstembodiment power supply;

FIG. 7 is a first field effect transistor (FET) driver of the firstembodiment power supply;

FIG. 8 is a second field effect transistor (FET) driver of the firstembodiment power supply;

FIG. 9 is a third field effect transistor (FET) driver of the firstembodiment power supply;

FIG. 10 a fourth field effect transistor (FET) driver of the firstembodiment power supply;

FIG. 11 is a capacitor set for use in the first embodiment power supply;

FIG. 12 is a capacitor set for use in the first embodiment power supply;

FIG. 13 is a capacitor set for use in the first embodiment power supply;

FIG. 14 is a capacitor set for use in the first embodiment power supply;

FIG. 15 is an input and ground for use in the first embodiment powersupply;

FIG. 16 is an isolated power supply transformer circuitry of the firstembodiment power supply;

FIG. 17 is a first tap circuitry of the first embodiment power supply;

FIG. 18 is a second tap circuitry of the first embodiment power supply;

FIG. 19 is a third tap circuitry of the first embodiment power supply;

FIG. 20 is a microcontroller circuitry first portion of the firstembodiment power supply;

FIG. 21 is a microcontroller circuitry second portion of the firstembodiment power supply;

FIG. 22 is a microcontroller circuitry third portion of the firstembodiment power supply;

FIG. 23 is an oscillator circuitry of the first embodiment power supply;

FIG. 24 is a capacitor set for use in the first embodiment power supply;

FIG. 25 is an overcharge protection circuitry first portion of the firstembodiment power supply;

FIG. 26 is an overcharge protection circuitry second portion of thefirst embodiment power supply;

FIG. 27 is a programmable logic first portion of the first embodimentpower supply;

FIG. 28 is a programmable logic second portion of the first embodimentpower supply;

FIG. 29 is a programmable logic third portion of the first embodimentpower supply;

FIG. 30 is a programmable logic fourth portion of the first embodimentpower supply;

FIG. 31 is a programmable logic fifth potion of the first embodimentpower supply;

FIG. 32 is a programmable logic sixth potion of the first embodimentpower supply;

FIG. 33 is a programmable logic seventh potion of the first embodimentpower supply;

FIG. 34 is a programmable logic eighth potion of the first embodimentpower supply;

FIG. 35 is a programmable logic ninth potion of the first embodimentpower supply;

FIG. 36 is a programmable logic tenth potion of the first embodimentpower supply;

FIG. 37 is a programmable logic eleventh potion of the first embodimentpower supply;

FIG. 38 is a programmable logic twelfth potion of the first embodimentpower supply;

FIG. 39 is a zero current predictor of the first embodiment powersupply;

FIG. 40 is a capacitor set for use in the first embodiment power supply;

FIG. 41 is a schematic of a power supply switch of a type that can beused with at least some embodiments of the present invention; and

FIG. 42 is a graph showing a variable frequency, variable duty cyclerelationship.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The following exemplary embodiment(s) of a switching power supply willbe given in the context of a switching power supply used in a batterydevice. More particularly, the battery device (not separately shown inthe Figs.) includes the switching power supply and rechargeableelectrochemical cells (preferably lithium ion or lithium polymer cells)in a housing. One or more jacks at an external surface of the housingallow external devices to be electrically connected and disconnectedfrom the switching power supply. Because it is electrically interposedbetween the external device(s) and the electrochemical cells, theswitching power supply here controls the charging and discharging of theelectrochemical cells. Specifically, an external power source can beconnected via a jack to recharge the electrochemical cells when theyhave been drained of charge. Alternatively (or additionally) an externalload can be connected. This external load can then be powered by theelectrochemical cells via the switching power supply. In some preferredembodiments of the present invention, only one jack is provided, andthis jack is used both to charge and discharge the electrochemicalcells.

The voltage regulation and other functionality provided to the batterydevice by the switching power supply can preferably handle both amultiple external charging source voltage levels and multiple externalload voltage levels. This robustness with respect to voltage levels ofthe external devices helps make the battery device compatible with agreater variety of charging sources and/or external load applications.Also, it is preferable that the switching power supply have a highelectrical power efficiency. For these reasons, the switching power ofthe present invention supports six modes of operation: (1) buck charge;(2) buck discharge; (3) boost charge; (4) boost discharge; (5) off; and(6) pass through.

Although the switching power supply is explained in terms of itsspecific role in this battery device with its electrochemical cells, itis strenuously noted that switching power supplies of the presentinvention are not limited to this application. All kinds of electricaldevices, such as general purpose computers, use switching power suppliesand the present invention is accordingly widely applicable to a widerange of applications now known or to be developed in the future.Although the regulation in other electrical devices will not generallybe considered as charge and discharge voltage, the bi-directionalregulation feature will often be helpful in contexts besideselectrochemical cell charging and/or discharging. Also, many of theother features, such as high electrical power efficiency, will also bebeneficial across many applications of the switching power supplies ofthe present invention.

The circuitry and operation of exemplary switching dc-dc converter powersupply 50 will now be discussed with reference to FIGS. 1 to 42. In thisexemplary embodiment, the dc-dc converter power supply is used inconjunction with rechargeable electrochemical cells (not shown). Moreparticularly, one side of the power supply is connected across a set ofelectrochemical cells and the other side is connected to an externalsource or load. When the power supply is connected to an outside sourceof electrical power, the electrochemical cells are charged. The powersupply makes sure that appropriate charging voltages are supplied to thecells, despite possible fluctuations or variances in the externalcharging supply. The power supply can also help prevent overcharging ofthe cells. On the other hand, when an external load is connected to thepower supply, the power supply converts power discharged from the cellsinto power of an appropriate level and regulation for the external load.The power supply is robust because it can operate in any one of fivemodes: (1) boost charging mode; (2) boost discharging mode; (3) buckcharging mode; (4) buck discharging mode; and (5) pass mode. While theexemplary power supply 50 is in some ways tailored to this rechargeableelectrochemical cells application, it should be understood that thepresent invention is not necessarily so limited and that power supply 50and/or other power supplies within the scope of the present inventionmay be used in a wide range of other power supply applications.

Supply 50 includes analog front end first portion 100; analog front endsecond portion 101; battery control first portion 225; battery controlsecond portion 226; display and equalization first portion 300; displayand equalization second portion 400; first field effect transistor (FET)driver 475; second field effect transistor (FET) driver 525; third fieldeffect transistor (FET) driver 575; fourth field effect transistor (FET)driver 625; isolated power supply transformer circuitry 900; first tapcircuitry 950; second tap circuitry 975; third tap circuitry 1000;microcontroller circuitry first portion 1025; microcontroller circuitrysecond portion 1100; microcontroller circuitry third portion 1125;oscillator circuitry 1200; overcharge protection circuitry first portion1300; overcharge protection circuitry second portion 1350; programmablelogic first portion 1400; programmable logic second portion 1450;programmable logic third portion 1500; programmable logic fourth portion1550; programmable logic fifth potion 1600; programmable logic sixthpotion 1625; programmable logic seventh potion 1650; programmable logiceighth potion 1675; programmable logic ninth potion 1700; programmablelogic tenth potion 1710 ; programmable logic eleventh potion 1720;programmable logic twelfth potion 1730; and zero current predictor 1750.

Referring to FIG. 1 a, analog front end first portion 100 includesinputs 102, 104, 138, 162; outputs 103, 105, 166; terminals 106, 112,139, 148, 164; grounds (digital or analog, as appropriate) 110, 116,136, 144, 154, 165; resistors 118, 122, 124, 132, 134, 140, 142, 152,158; capacitors 120, 126, 146, 156; six port processing circuit 160;operational amplifiers 114, 150; digital-to-analog (D/A) converter 108;and two diode package 128.

The circuit elements of the analog front end first portion areelectrically interconnected as shown in FIG. 1 a. The followingparagraph sets forth preferred electrical characteristics for some ofthe elements of the analog front end first portion. For proper readingof this kind of electrical characteristics paragraph throughout thisdocument, unless otherwise noted: (1) the notation DNP means Do NotPopulate; (2) terminal values are given in volts; (3) resistor valuesare given in ohms; (4) capacitor values are give in picofarads (pF),nanofarads (nF) or microfarads (μF); (5) inputs are matched tocorresponding outputs; and (6) outputs are matched to correspondinginputs.

Preferred electrical characteristics for some of the components are nowset forth in parentheses after each element: input 102 (serial data portB); input 104 (serial clock port B); input 138 (Charge Supply); input162 (Charge Discharge); output 103 (input 107); output 105 (input 109);output 166 (Duty Cycle Control); terminal 106 (+5.4); terminal 112(+5.4); terminal 139 (+5.4); terminal 148 (+5.4); terminal 164 (+5.4);resistor 118 (1M0); resistor 122 (0R); resistor 124 (DNP); resistor 132(10K0); resistor 134 (10K0); resistor 140 (1M0); resistor 142 (143K);resistor 152 (1K0); resistor 158 (1K0); capacitor 120 (4700 pF);capacitor 126 (4700 pF); capacitor 146 (1000 pF); capacitor 156 (1K0);circuit 160, port 1 (Select); circuit 160, port 2 (V+); circuit 160,port 3 (GND); circuit 160, port 4 (NO); circuit 160, port 5 (COM); andcircuit 160, port 6 (NC).

Converter 108 converts from digital to analog a signal representing thevoltage that the power supply is to regulate. Preferably, convertermodel number MAX5382L from Maxim/Dallas of Sunnyvale, Calif. is used asconverter 108 because of: (1) its 12C interface; and (2) adequateresolution.

Operational amplifier 114 generates an analog signal proportional to thedifference between the actual output voltage and the desired outputvoltage. Operational amplifier 150 converts actual output voltage into asignal for comparison with signal generated by 108. Preferably modelnumber TC1034 from Microchip of Chandler, Ariz. is selected foroperational amplifiers 114, 150 because of its: (1) low powerconsumption; (2) rail to rail input output capability; and (3) smallpackage size.

Processing circuit 160 selects one of two signals generated by the erroramplifiers to feed to the oscillator on operating mode (e.g., boostcharging, boost discharging, buck charging, buck discharging, pass).Preferably processing circuit 160 is selected as an NLAS4599 AnalogSwitch from ON Semiconductor because of; (1) small package size; and (2)low power consumption.

Referring to FIG. 1 b, analog front end second portion 101 includesinputs 107, 109, 174, 176, 200; output 186; terminals 178, 182, 204,211, 234; grounds (digital or analog, as appropriate) 172, 188, 212,216, 230; resistors 180, 190, 194, 196, 202, 208, 210, 220, 232, 236;capacitors 192, 198, 214, 218; operational amplifiers 184, 206; D/Aconverter 170; and two diode package 130. The circuit elements of theanalog front end second portion are electrically interconnected as shownin FIG. 1 b.

Preferred electrical characteristics for some of the elements of theanalog front end second portion are now set forth in parentheses aftereach element: input 107 (output 103); input 109 (output 105); input 174(serial clock port B); input 176 (serial data port B); input 200 (IS+);output 186 (Ireg monitor); terminal 178 (+5.4); terminal 182 (+5.4);terminal 204 (+5.4); terminal 211 (+5.4); terminal 234 (+5.4); resistor180 (100K); resistor 190 (1M0); resistor 194 (0R); resistor 196 (DNP);resistor 202 (100K); resistor 208 (1K0); resistor 210 (976K); resistor220 (1K0); resistor 232 (2K05); resistor 236 (22K1); capacitor 192 (100pF); capacitor 198 (100 pF); capacitor 214 (0.1 μF); capacitor 218 (100pF).

Converter 170 converts from digital to analog a signal representingregulated current. Preferably, converter 170 is similar in constructionto converter 108 discussed above. Operational amplifier 184 ispreferably similar in construction to operational amplifier 114discussed above, but operational amplifier 184 generates an error signalfor current instead of voltage. Operational amplifier 206 is preferablysimilar in construction to operational amplifier 150 discussed above,but operational amplifier amplifies the current signal instead ofvoltage. As shown in FIGS. 1 a and 1 b, two diode packages 128, 130 worktogether to allow only the correct signal to pass to processing circuit160. Specifically, only the higher or lower of the voltage and currenterror signal may pass, dependant on the operating mode of the converter.The two diode packages are preferably constructed as model BAV199LT1from ON Semiconductor of Phoenix, Ariz.

FIG. 2 shows capacitor set 75 including +5.4 V terminal 77, ground 79and eight parallel-connected, 0.1 μF capacitors 81. Capacitor set 75 aredecoupling capacitors respectively associated with the ICs of FIGS. 1 aand 1 b.

Now that the circuitry of analog front end 100, 101 has been identified,its functionality will be briefly discussed. Generally speaking, theanalog front end detects what can be considered as feedback ordiagnostic information to compare the difference between the status ofpower flow in the switching power supply and the target levels of powerflow that are desired at a given time. The switching power supply usesthis feedback information to help control its switching operations on anongoing basis so that dc-dc conversion and other power flow functionsare controlled to be sufficiently close to desired levels.

More particularly, the analog front end compares the actual convertervoltage and current with the desired voltage and current limits set bythe microprocessor. The analog front end also generates an error voltagedependant on mode for input to the oscillator stage. The front endamplifiers are tuned circuits to provide the correct phase and gainresponse as a function of frequency to provide stable operationalcontrol. Voltage and current limiting work independent of one another,but provide a common error signal to the oscillator stage.

Referring to FIG. 3 a, battery control first portion 225 includes input249; outputs 233, 234, 236, 250; ground (digital or analog, asappropriate) 243; resistor 251; capacitor 231; DC jack terminals 227,247; and input overvoltage protection circuit 229; and Metal OxideSemiconductor Field Effect Transistor (“MOSFET”) 245. The circuitelements of the battery control first portion are electricallyinterconnected as shown in FIG. 3 a.

Preferred electrical characteristics for some of the components of thefirst battery control portion are now set forth in parentheses aftereach element: input 249 (Overcharge); output 233 (Charge Supply); output234 (input 244); output 236 (input 246); output 250 (Jack Sense); andresistor 251 (1M0).

Capacitor 231 is preferably formed as a set of four parallel-connectedcapacitors, including two variable capacitors and two fixed 10 μFcapacitors. Jack terminals 227, 247 allow the positive side of theinput/output to be connected to external components (such as chargingsources and discharging loads). Input overvoltage protection circuit 229includes two transorbs and a polyswitch as shown in FIG. 3a. Thetransorbs behave like Zener diodes and will give off heat as voltageincreases into an overvoltage. The polyswitch acts as a resettablethermal fuse. In the event of overvoltage, heat from the transorbs tripsthe polyswitch to thereby eliminate the overvoltage condition.Alternatively, other types of overvoltage protection, now known or to bedeveloped in the future, could be used. MOSFET 245 prevents overchargeand is basically a switch that turns off in the event of potentialovercharging. MOSFET 245 is preferably constructed as Model Si4886DYfrom Vishay Siliconix of Shelton, Conn.

Referring to FIG. 3 b, battery control second portion 226 includesinputs 237, 241, 244, 246, 271, 275, 281, 283; outputs 261, 263;capacitor 273 (preferably constructed similar to capacitor 231);inductors 253, 255; grounds (digital or analog, as appropriate) 257,267, 277; precision voltage dividers 259, 265; and MOSFETs 235, 239,269, 279. The circuit elements of the battery control second portion areelectrically interconnected as shown in FIG. 3 b. Preferred electricalcharacteristics for some of the elements of the battery control secondportion are now set forth in parentheses after each element: input 237(Series a Gate); input 241 (Shunt a Gate); input 244 (output 234); input246 (output 236); input 271 (Series B Gate); input 275 (Shunt B Gate);output 261 (Node A Signal); output 263 (Node B Signal); input 281(Battery +); and input 283 (Battery −).

MOSFETS 235, 269 are preferably constructed as Model Si4835DY fromVishay Siliconix. MOSFETS 239, 279 are preferably constructed as ModelSi4886DY from Vishay Siliconix. Inductors 253, 255 are preferably each3.2 microhenry inductors with a saturation current of at least 8.6amperes (A) at 25 degrees Celsius (C). Of course, the combinedinductance of these inductors connected in series is 6.4 microhenry.Alternatively, one larger inductor could be used here, but it isgenerally easier to obtain two small inductors rated at this high levelof saturation current. Precision voltage dividers 259, 265 (or resistornetworks) are preferably constructed as Model MPM2001/1002A from VishayThin Film of Shelton, Connecticut. In power supply 50, these MOSFETS235, 239, 269, 279 are the power supply switches. In other power supplyembodiments, other types of FETs, or other types of transistors, or evenentirely different types of semiconductor devices, may be used for thepower supply switches. Power supply switches are sometimes hereinreferred to as “power supply switch FETs.”

Now that the circuitry of battery control 225, 226 has been identified,its primary functionality will be briefly discussed. Switching powersupplies use passive (e.g., inductors, capacitors) and active (e.g.,switches) components, working in conjunction, to accomplish the desiredregulation (generally voltage regulation). In power supply 50, thepassive components are capacitors 231, 271 and inductors 253, 255. TheMOSFETs 235, 239, 269, 279 are the active components, or switches, ofswitching power supply 50. These four MOSFETs are structured toaccomplish the five modes operation of power supply operation asidentified above.

The precision voltage dividers 259, 265 are used to divide the voltageson either side of the inductor. The inductor voltage is used to predicta zero current condition and thereby help control in the efficientoperation of the switching power supply. However, the voltage is dividedbecause it is a high voltage that could damage the components used inmaking the zero current predictions. Alternatively, other hardware, nowknown or to be developed in the future, could be used to effect anynecessary voltage decreases required by the zero current predictioncircuitry.

Preferred switching power supplies according to the present inventionhave electrical power efficiencies (e.g., at 25 watt, full power) ofupwards of 95%, 98% or even 99%. Some of the features that result in thevery high efficiencies of the present invention are related to thedriving of the power supply switches, in this embodiment MOSFETs 235,239, 269, 279. Some inefficiencies in switching power supplies include:(1) gate charge of MOSFETS (active component set, frequency sensitive);(2) resistance drain to source (“RDS”, active component set); (3)resistance loss of inductor (dc loss, frequency sensitive, less loss athigh frequency); (4) capacitive losses (frequency sensitive, ESR:effective series resistance); (5) shunt loss (smaller shunt ispreferred, not frequency sensitive); and (6) frequency inductance.

The transient resistance of the MOSFETs cause switching losses. Thepresent invention reduces these switching losses through the use of highspeed switching (>15 nanosecond rising edge, >10 nanosecond rising edge)and driver circuitry capable of fast, clean operation.

Phantom switching in the MOSFETs is another source of switching losses.The present operation compensates for phantom switching by overbiasingthe gate voltages of the MOSFET power supply switches. Specifically, thegate voltage is adjusted, or biased, by some amount (typically 2 V) fromthe nominally expected values in whatever direction (+V, −V) will tendto compensate for phantom switching.

A schematic 1900 of power supply switch MOSFETs 235, 239, 269, 279 isshown in FIG. 41. There is in each MOSFET an inherent source-to-draincapacitance 1902, an inherent gate-to-source capacitance 1904 and aninherent gate-to-drain capacitance 1906. Please note that 1902, 1904 and1906 are not separate components, but rather hypothetical componentsthat model the way charge behaves inside a FET. The ratio ofgate-to-source capacitance to gate-to-drain capacitance is herein calledthe gate capacitance ratio. In a power supply switch that is high sidereferenced so that the gate voltage is nominally referenced to the drainvoltage, the gate voltage will tend to be pulled toward the sourcevoltage by the gate capacitance effect. The gate capacitance effect isthe absolute value of the difference between the source and drainvoltages multiplied by the gate capacitance ratio. The smaller the gatecapacitance ratio (e.g. >0.1, >0.05), the less the gate voltage will bepulled toward the source voltage.

While making a smaller gate capacitance ratio is one way to reduce thegate capacitance effect, overbiasing the gate reference voltage is a wayto systematically compensate for the gate capacitance effect. Moreparticularly, the driving circuitry that generates the gate referencevoltage preferably offsets (i.e., offsets away from the source voltagelevel) the gate reference voltage in an amount approximately equal tothe gate capacitance effect. For example, if source is at ground leveland drain is at 20 V, and the gate capacitance ratio is 0.05, then gatecapacitance effect equals |20V-0V|*0.05=1 volt. Therefore, the gatereference voltage would be about 20V+1V=21 V at this point to make upfor the gate capacitance effect. Overbiasing of the gate is especiallyhelpful when multiple power supply switches and synchronous operationgive rise to the possibility of phantom switching because theoverbiasing helps eliminate or reduce phantom switching.

Referring to FIG. 4, display and equalization first portion 300 includesinputs 322, 324, 330; outputs 306, 308, 310, 312; terminals 320, 350;ground (preferably digital) 304; resistors 314, 316, 318, 326, 332, 336,340, 344, 348, 352, 354, 356, 358; light emitting diodes (LEDs) 328,334, 338, 342, 346; and sixteen port processing circuit 302. The circuitelements of the display and equalization first portion are electricallyinterconnected as shown in FIG. 4. Preferred electrical characteristicsfor some of the elements of the display and equalization first portionare now set forth in parentheses after each element: input 322 (SerialData Port B); input 324 (Serial Clock Port B); input 330 (LED 1); output306 (Equalization 4); output 308 (Equalization 3); output 310(Equalization 2); output 312 (Equalization 1); terminal 320 (+5.4 V);terminal 350 (+5.4 V); resistor 314 (100K); resistor 316 (100K);resistor 318 (100K); resistor 326 (100K); resistor 332 (1K0); resistor336 (1K0); resistor 340 (1K0); resistor 344 (1K0); resistor 348 (1K0);resistor 352 (100K); resistor 354 (100K); resistor 356 (100K); resistor358 (100K); LED 328 (Red); LED 334 (Yellow); LED 338 (Green); LED 342(Green); LED 346 (Green); port 1 of circuit (or “ckt”) 302 (A0); port 2of ckt 302 (A1); port 3 of ckt 302 (A2); port 4 of ckt 302 (LED0); port5 of ckt 302 (LED1); port 6 of ckt 302 (LED2); port 7 of ckt 302 (LED3);port 8 of ckt 302 (GND); port 9 of ckt 302 (LED4); port 10 of ckt 302(LED5); port 11 of ckt 302 (LED6); port 12 of ckt 302 (LED7); port 13 ofckt 302 (RESET); port 14 of ckt 302 (SCL); port 15 of ckt 302 (SDA); andport 16 of ckt 302 (VDD).

Processing circuit 302 is preferably structured as an 8-bit 12C LEDDriver (with programmable blink rates), model PCA9551 made by PhilipsSemiconductors of the Netherlands. Processing circuit 302 receivessignals in I2C, serial format from the main microprocessor and convertsthese into parallel signals, such as: (1) parallel signals used tocontrol LEDs 328, 334, 338, 342, 346; and (2) parallel signals used tocontrol charging equalization (further discussed below). The I2C formatsignal are input to processing circuit 302 through ports 14 and 15. Theparallel signals for controlling the LEDs are output through processingcircuit 302 ports 9 to 18. The parallel signals for controlling chargingequalization are output through processing circuit 302 ports 4 to 7. Onefeature of the I2C to parallel communications interface of processingcircuit 302 is that it separates the LED drive circuitry from directmicroprocessor current. This is beneficial because the microprocessortypically makes very sensitive voltage measurements. Another feature ofthe I2C to parallel communications interface of processing circuit 302is that this scheme frees up microprocessor pins because the serial I2Cversion of the communications, output by the microprocessor) requiresfewer pins than the parallel LED-related and equalization-relatedversions of the same communications as output by processing circuit 302.

FIG. 5 shows decoupling capacitor set 375 including +5.4 V terminal 381,ground 383; 0.1 microfarad (μF) capacitor 377; and 1 μF capacitor 379.Capacitors 377 and 379 are connected in parallel. Capacitor set 375 isconnected between the +5.4 supply rail and digital ground, electricallyproximate to processing circuit 302. The use of both 0.1 μF and 1 μFcapacitors causes decoupling at both high and low frequencies.

Referring to FIG. 6, display and equalization second portion 400includes inputs 416, 426, 436, 446; outputs 408, 410, 452, 454, 456,458, 460; terminals 419, 429, 439, 449; grounds (preferably digital)406, 412, 422, 432, 442; resistors 404, 418, 420, 428, 430, 438, 440,448, 450; NPN bipolar transistors 414, 424, 434, 444; and ten portconnector 402. The circuit elements of the display and equalizationsecond portion are electrically interconnected as shown in FIG. 1 b.Preferred electrical characteristics for some of the elements of thedisplay and equalization second portion are now set forth in parenthesesafter each element: input 416 (Equalization 1); input 426 (Equalization2); input 436 (Equalization 3); input 446 (Equalization 4); output 408(Battery−); output 410 (IS+); output 452 (Cell 1); output 454 (notconnected); output 456 (Battery+); output 458 (Cell 3); output 460 (Cell2); terminal 419 (+5.4 V); terminal 429 (+5.4 V); terminal 439 (+5.4 V);terminal 449 (+5.4 V); resistor 404 (5 mOhm Cu Track); resistor 418(301K); resistor 420 (0R); resistor 428 (301K); resistor 430 (0R);resistor 438 (301K); resistor 440 (301K); resistor 448 (301K); andresistor 450 (301K).

Connector 402 is preferably structured as a 2 by 5, 25 square headerconnector. The circuitry and electronics of power supply 50 arepreferably mounted on a control board (not shown). The electrochemicalcells charged and discharged by power supply 50 are preferably mountedon an interconnect board (or frame). Connector 402 (mounted on thecontrol board) electrically connects the control board to theinterconnect board, and to the electrochemical cells (preferably fourconnected in series) themselves. Transistors 414, 424, 434, 444 act asswitches for equalization resistors (not shown in FIG. 6, but preferablylocated on the control board).

More particularly, it is preferred that the electrochemical cells chargeat (at least) roughly even rates and/or at a roughly equal chargedcapacity over the recharging process. Therefore, an equalizationresistor is selectively connected in parallel with each electrochemicalcell. When an electrochemical cell is charging too quickly, the parallelbypass resistor can be turned on by the corresponding transistor 414,424, 434, 444. If an electrochemical cell is charging too slowly thenits bypass resistor can be disconnected by turning off the correspondingtransistor switch. As mentioned previously, the parallel formatequalization signals EQ1, EQ2, EQ3, EQ4 to control the on-off state ofthe transistors is received from processing circuit 302 based on I2Csignals from the microprocessor. In this way, the microprocessorcontrols cell charging rates and/or relative charged capacities. It isnoted that in other embodiments, other types of charging control may bedesired (e.g., preferentially charge/discharge one of the cells relativeto the others). The above-discussed control signals and transistors 414,424, 434, 444 also provide a mechanism to effect these other,non-preferred types of control.

Four FET driver circuits 475, 525, 575, 625 will now be explained withreference to FIGS. 7, 8, 9 and 10, respectively. Referring to FIG. 7,first FET driver 475 includes input 496; output 519; ground (preferablyanalog) 515; resistors 481, 487, 489, 493, 495, 503, 507, 511, 523;capacitors 479, 513; terminals 477, 491, 501, 505; diode 483; bipolartransistors 517, 521; and FETs 485, 497, 499, 509, 510. Preferredelectrical characteristics for some of the elements of first FET driver475 are set forth in parentheses in the following list: input 496(Seriesa_In); output 519 (Seriesa_Gate); resistor 481 (4K99); resistor487 (301K); resistor 489 (100K); resistor 493 (24R9); resistor 495(301K); resistor 503 (24R9); resistor 507 (4K99); resistor 511 (100K);resistor 523 (100K); capacitor 479 (1000 pF); capacitor 513 (0.01 μF);terminal 477 (V1+); terminal 491 (V1+); terminal 501 (V1−); and terminal505 (V1−). Diode 483 is preferably model number BAV70 (see webpagehttp://www.fairchildsemi.com/cqpf/BA/BAV70.html for further informationon component BAV70). Bipolar transistor 517 is preferably model numberFMMT619CT. Bipolar transistor 521 is preferably model number FMMT720CT.

Referring to FIG. 8, second FET driver 525 includes input 546; output569; ground (preferably analog) 565; resistors 531, 537, 539, 543, 545,553, 557, 561, 573; capacitors 554, 529, 563; terminals 527, 541, 551,555; diode 533; bipolar transistors 567, 571; and FETs 535, 547, 549,559, 560. Preferred electrical characteristics for some of the elementsof second FET driver 525 are set forth in parentheses in the followinglist: input 546 (Seriesb_in); output 569 (Seriesb_Gate); resistor 531(4K99); resistor 537 (301K); resistor 539 (100K); resistor 543 (24R9);resistor 545 (301K); resistor 553 (24R9); resistor 557 (4K99); resistor561 (100K); resistor 573 (100K); capacitor 554 (1000 pF); capacitor 529(1000 pF); capacitor 563 (0.01 μF); terminal 527 (V3+); terminal 541(V3+); terminal 551 (V3−); and terminal 555 (V3−). Diode 533 ispreferably model number BAV70. Bipolar transistor 567 is preferablymodel number FMMT619CT. Bipolar transistor 571 is preferably modelnumber FMMT720CT.

Referring to FIG. 9, third FET driver 575 includes input 596; output619; resistors 581, 587, 589, 593, 595, 603, 607, 623; capacitors 604,579; terminals 577, 591, 601, 605; diodes 583, 610; bipolar transistors617, 621; and FETs 585, 597, 599, 609. Preferred electricalcharacteristics for some of the elements of third FET driver 575 are setforth in parentheses in the following list: input 596 (Shunta_In);output 619 (Shunta_Gate); resistor 581 (4K99); resistor 587 (301K);resistor 589 (301K); resistor 593 (24R9); resistor 595 (DNP); resistor603 (24R9); resistor 607 (4K99); resistor 623 (100K); capacitor 604(1000 pF); capacitor 579 (1000 pF); terminal 577 (V2+); terminal 591(V2+); terminal 601 (V2−); and terminal 605 (V2−). Diodes 583, 610 arepreferably model number BAV70. Bipolar transistor 617 is preferablymodel number FMMT619CT. Bipolar transistor 621 is preferably modelnumber FMMT720CT.

Referring to FIG. 10, fourth FET driver 625 includes input 646; output669; resistors 631, 637, 639, 643, 645, 653, 657, 673; capacitors 654,629; terminals 627, 641, 651, 655; diodes 633, 660; bipolar transistors667, 671; and FETs 635, 647, 649, 659. Preferred electricalcharacteristics for some of the elements of fourth FET driver 625 areset forth in parentheses in the following list: input 646 (Shuntb_In);output 669 (Shuntb_Gate); resistor 631 (4K99); resistor 637 (301K);resistor 639 (301K); resistor 643 (24R9); resistor 645 (DNP); resistor653 (24R9); resistor 657 (4K99); resistor 673 (100K); capacitor 654(1000 pF); capacitor 629 (1000 pF); terminal 627 (V2+); terminal 641(V2+); terminal 651 (V2−); and terminal 655 (V2−). Diodes 633, 660 arepreferably model number BAV70. Bipolar transistor 667 is preferablymodel number FMMT619CT. Bipolar transistor 671 is preferably modelnumber FMMT720CT.

The four FET drivers 475, 525, 575, 625 respectively handle controlsignals for the four power supply switches, specifically MOSFETS 235,269, 239, 279 (see FIG. 3 b and related discussion). The operation ofeach of the four FET drivers is quite similar, so only the operation ofFET driver 475 will be discussed now in detail. FET driver 475 handlescontrol output signals, that is, the signals sent from the controller toa power supply switch (in this example, MOSFET 235) to control theon-off operation of that power supply switch. More particularly, thesome features of FET driver 475 relate to: (1) a capacitive coupling inthe path transmitting the control output signal; (2) use of a pinkeepercircuitry in the path transmitting the control output signal; and/or (3)use of a path suitable for draining gate capacitance charge from a powersupply switch. It should be kept in mind that at least some of thefeatures explained in this context will have applicability to otherswitching power supplies (now extant and to be developed in the future)having various hardware layouts, topologies, etc.

This conversion of the control output signals from one form to anotherby FET driver 475 will now be explained. Specifically, the conversion ofthe Seriesa_In control output signal 496 into the form of thecorresponding Seriesa_Gate control output signal 519 will be explainedwith reference to FIG. 7. FET driver 475 may be more genericallyreferred to as a power supply switch driver. As shown in FIG. 7, theSeriesa_In signal 496 (from the controller) is provided as an input atthe left side of FET driver 475. FET driver 475 converts the Seriesa_Insignal into the corresponding Seriesa_Gate signal 519, which is providedas an output on the right side of FET driver 475. Three aspects of FETdriver 475 will now be discussed: (1) capacitive coupling; (2)pinkeeper; and (3) path suitable for draining gate capacitance chargefrom a power supply switch.

FET driver 475 includes capacitors 479, 504. These two capacitors form acapacitive coupling (alternatively, there could be more or fewerindividual capacitors in the capacitive coupling). More particularly,there is no direct (or dc) path between the Seriesa_In input 496 and theSeriesa_Gate output 519. Communication of the control output signaltherefore goes through this capacitive coupling.

In the preferred embodiment, the Seriesa_In signal is in the form of a 5volt, digital ground referenced square wave (e.g., 0 volts for off, 5 Vfor on). Most of the time, during the flat stay-off or stay-on portions,this Seriesa_In square wave signal has only a dc component. This dccomponent does not get communicated through the capacitive coupling.However, the rising and falling of the square wave involve highfrequency components, as would be revealed by a Fast Fourier Transform.These high frequency components, these rising or falling edges, arecommunicated through the capacitive coupling. Specifically, the risingand falling edges cause short duration positive and negative voltagespikes on the right side of FET driver 475.

Therefore, in this preferred embodiment, wherein a square wave formatcontrol output signal is communicated through a capacitive coupling tobecome a signal characterized by voltage spikes (herein called anintermediate control output signal because it is an intermediate form ofthe control output signal between the Seriesa_In form and theSeriesa_Gate form). However, it is noted that alternative embodimentsmay use other electrical signal patterns, while still effectingcommunication through a capacitive coupling. For example, the controloutput signal could be in the form of voltage spikes prior to beingcommunicated by the capacitive coupling. At least in theory, any controloutput signal with a substantial high frequency component can becommunicated through a capacitive coupling in some fashion.

At least theoretically, the intermediate control output signal coulddirectly be used to control a power supply switch. Of course, the powersupply switch would need to be designed to be turned on or off (andquickly so) by positive and negative voltage spikes. Such an embodimentof the present invention would potentially have many of the advantagesof capacitive coupling, as will be explained below. However, in powersupply 50, the power supply switches are constructed as FETs 235, 269,239, 279, which are referenced at around the relatively high voltages ofelectrochemical cells (e.g., 10V to 20V). The voltage spikes of theintermediate signal are insufficient to directly control the FET powersupply switches of preferred embodiment 50 for reasons including thefollowing: (1) the amplitude (that is, absolute voltage level) of thespikes are too low to operate the power supply switch FET (which isoperating at battery voltage type levels); and (2) the spikes have ashort time duration, while the gate terminal of the power supply switchFET must be driven by a continuous voltage.

In order to make the spike-form intermediate control output signalcontrol the power supply switch 235, the intermediate control outputsignal is converted into the Seriesa_Gate signal 519 by the pinkeepercircuitry included in FET driver 475. The pinkeeper circuitry includesFETs, bipolar transistors and resistors as shown in FIG. 7. Theprinciples of operation of the pinkeeper circuitry are conventional andwill therefore not now be discussed in component by component detailhere. For present purposes, the hardware details of the pinkeepercircuitry isn't as important as the idea of using pinkeeper circuitry inconjunction with a control output signal for a power supply switch setin a switching power supply.

Generally speaking, the pinkeeper circuitry of FET driver 475 uses thepositive and negative voltage spikes of the intermediate control outputsignal to latch the Seriesa_Gate control output signal at a high or alow level. The voltage values for the high and low levels will dependupon battery voltage, power supply FET switch polarity, overbiasing andso on. The FET driver circuitry is typically where the overbiasing ofthe gate reference voltage to compensate for gate capacitance effect isapplied to the driver signal. The latched Seriesa_Gate signal is appliedto the gate terminal of the series a power supply FET switch 235. WhenSeriesa_Gate is latched in one voltage state (say, low voltage level),this turns and maintains the power supply FET switch off. WhenSeriesa_Gate is latched in the other voltage state (say, high voltagelevel), this turns and maintains the power supply FET switch on. Thepinkeeper circuitry is bi-stable. That is, the pinkeeper circuitryreliably maintains Seriesa_Gate in a high or low (that is, on or off)state, changing only in response to spikes in the intermediate controloutput signal.

Now that the operation of the capacitive coupling and the pinkeepercircuitry have been discussed, discussion will move to the path suitablefor draining gate capacitance charge from a power supply switch, builtinto FET driver 475. Assume that a step change in the voltage of theSeriesa_In control output signal causes a voltage spike in theintermediate control output signal. This spike turns on FET 509 (seeFIG. 7). Turning on FET 509 causes current to be pulled through bipolartransistor 521. Pulling current through bipolar resistor 521 pulls theSeriesa_Gate control output signal down toward voltage level V2−. Whenthe Seriesa_Gate signal reaches voltage V1− it will turn the Seriesapower supply FET switch 235 on or off (depending on polarity of theseries a power supply FET switch). In this electrical scheme, FET 509 isa low impedance path. This current drain quickly drains the gatecapacitance of the series a power supply FET switch.

Because the gate capacitance is quickly drained, the Series_a powersupply FET switch 509 turns on and off quickly. Also, any overbiasing ofthe gate capacitance will be accomplished more quickly because of thelow impedance current path. This quick on-off operation of the powersupply FET switch 509 reduces switching losses and/or transition lossesand thereby improves efficiency. For example, a rise time as low as 10nanoseconds has been observed. That is very quick.

The capacitive coupling, pinkeeper and current path features embodied inconversion circuitry 202 (whether considered individually or incombination) has several potential objectives, features and/oradvantages:

(1) Control output signal can be generated at one reference level by thecontroller circuitry (e.g., digital ground referenced), but can stillcontrol a power supply switch referenced at a different level (e.g.,power supply FET switch referenced at the analog voltage of anelectrochemical cell); the feature of having two (or more) differentreference levels for a control output signal is facilitated by thecapacitive coupling;

(2) Control output signal can be generated at one voltage amplitudelevel by the controller circuitry (e.g., 5 V over digital ground foron), but can still control a power supply switch responsive to adifferent level control signal (e.g., power supply FET switch operatedwith overbiasing); the feature of having two (or more) differentamplitude levels for a control output signal is facilitated by thecapacitive coupling;

(3) The control output signal generated by the controller does not needto actively and/or continuously drive the power supply switch; thisfeature is facilitated by the pinkeeper and its latching;

(4) Switching losses and associated rise and fall times associated withthe switching of a power supply switch are reduced; this is facilitatedby the capacitive coupling; for example, the capacitive couplingfacilitates a reduction in switching losses in the sense that thecontrol output signal reference level and amplitude level can bemanipulated by virtue of the capacitive coupling so that faster powersupply switch driver components can be chosen and/or so that powersupply switch driver components can be operated well below their voltageand/or speed limitations;

(5) Switching losses and associated rise and fall times associated withthe switching of a power supply switch are reduced; this is facilitatedby the low impedance path and/or appropriate capacitors for alternatelydraining and supplying charge of the gate capacitance of the powersupply switch (e.g., FET switch);

(6) Allows quicker and/or amore accurate overbiasing of power supplyswitch (e.g., power supply FET switch);

(7) Prevents phantom switching;

(8) Improves power supply efficiency and reduces heat generated in powersupply switch (e.g., FET switch) during rides and falls of the operativecontrol output signal;

(9) Bipolar transistor used to help form a low impedance path for gatecapacitance of a power supply switch; and

(10) use of what is effectively a high gain current amplifier.

FIGS. 11 to 14 show capacitor sets 800, 825, 850, 875 respectively usedin conjunction with FET drivers 235, 239, 269, 279. The capacitor sets800, 825, 850, 875 absorb the gate capacitance of a corresponding powersupply FET switch 235, 239, 269, 279 when it is turned off. Thecapacitor sets also supply charge to help restore the gate capacitancewhen the corresponding power supply FET switch is turned on again. Forexample, capacitor set 800 is connected across the V1+/V1− terminals ofFET driver 475 and exchanges charge with the Seriesa power supply FETswitch 235. FIG. 11 shows capacitor set 800 including V1+ terminal 802,V1− terminal 808, Charge Supply input 814, 0.1 μF capacitors 804, 808and 0.01 μF capacitors 810, 812. FIG. 12 shows capacitor set 825including V2+ terminal 827, V2− terminal 833, ground 837, 0.1 μFcapacitors 829, 831 and 0.01 μF capacitors 835, 839. FIG. 13 showscapacitor set 850 including V2+ terminal 852, V2− terminal 858, ground862, 0.1 μF capacitors 854, 856 and 0.01 μF capacitors 860, 864. FIG. 14shows capacitor set 875 including V3+ terminal 877, V3− terminal 883,Battery+ input 887, 0.1 μF capacitors 879, 881 and 0.01 μF capacitors885, 889.

FIG. 15 shows Batt− input 895 and ground 897. The circuitry of FIG. 15connects the Batt− signal to a (preferably analog) ground.

The circuitry of FIGS. 16 to 19 will now be explained by firstidentifying the constituent components in each of the Figs., followed bydiscussion of the operation of the circuitry and its role in switchingpower supply 50.

Referring to FIG. 16, isolated power supply transformer circuitry 900includes inputs 906, 934, 936; output 928; terminals 904, 918, 945;ground (preferably digital) 912; resistors 908, 914, 920, 948;capacitors 910, 916, 938, 949; core/winding assemblies 922, 940; diodes930, 932; Schottky diode 946; and switch mode regulator 902. The circuitelements of the isolated power supply transformer circuitry areelectrically interconnected as shown in FIG. 16. Preferred electricalcharacteristics for some of the elements of isolated power supplytransformer circuitry 900 are set forth in parentheses in the followinglist: input 906 (Power_Enable); input 934 (Batt+); input 936(Charge_Supply); output 928 (Control_Power); terminal 904 (+4.7 V);terminal 918 (+5.4 V_; terminal 945 (+5.4 V); resistor 908 (100K);resistor 914 (10K0); resistor 920 (33K2); resistor 948 (10R0); capacitor910 (10 μF); capacitor 916 (4.7 pF); capacitor 938 (1 μF); capacitor 949(10 μF); port 1 of regulator 902 (SW); port 2 of regulator 902 (GND);port 3 of regulator 902 (FB); port 4 of regulator 902 (VIN); and port 5of regulator 902 (SHDN). Diode 930, 932 are preferably model numberBAV70. Schottky diode 946 is preferably model number MA112CT.Core/winding assembly 922 is preferably model number T1AF4E-1810B+F4IE-1810B. Core/winding assembly 940 is preferably modelnumber TIE. Core/winding assemblies 922 and 940 include taps 924, 926,942, 944, which taps will be further discussed below.

Referring to FIG. 17, first tap circuitry 950 includes input 962;Schottky diodes 954, 972; terminals 960, 966; resistors 956, 970; Zenerdiode 964; capacitors 958, 968 and core/winding assembly 952. Thecircuit elements of the first tap circuitry are electricallyinterconnected as shown in FIG. 17. Preferred electrical characteristicsfor some of the elements of first tap circuitry 950 are set forth inparentheses in the following list: input 962 (Charge Supply); terminal960 (V1+); terminal 966 (V1−); resistor 956 (10R0); resistor 970 (10R0);capacitor 958 (1 μF); and capacitor 968 (1 μF). Schottky diodes 954, 972are preferably model number MA112CT. Zener diode 964 is preferably modelnumber BZX84C10-7. Further information on this component can be found atwebpage:

http://www.allamerican.com/direct/product.asp?T_PRDKEY=DIO+BZX84C107+++++++++++&T_MFGCOD=DIO+&T_PRDID=BZX84C10-7+++++++++++.

Core / winding assembly 952 will be further discussed below.

Referring to FIG. 18, second tap circuitry 975 includes circuit elements979, 981, 983, 989, 993, 995, 997 which are similar to theircounterparts in circuitry 950 identified above in connection with FIG.17. The second tap circuitry further includes V2+ terminal 985, V2−terminal 991 and (preferably analog) ground 995. The circuit elements ofthe second tap circuitry are electrically interconnected as shown inFIG. 18. Core/winding assembly 977 will be further discussed below.

Referring to FIG. 19, third tap circuitry 1000 includes circuit elements1004, 1006, 1008, 1014, 1018, 1020, 1022 which are similar to theircounterparts in circuitry 950 discussed above in connection with FIG.17. The third tap circuitry further includes V3+ terminal 1010, V3−terminal 1016 and Battery+ input 1012. The circuit elements of the thirdtap circuitry are electrically interconnected as shown in FIG. 19.Core/winding assembly 1002 will be further discussed below.

Now that the isolated power supply circuitry 900, 950, 975, 1000 hasbeen identified, its functionality will be discussed. The isolated powersupply circuitry receives input electrical, which it converts into powersignals of six voltage levels: V1+. V1−, V2+, V2−, V3+ and V3−. Thesesix voltages are used to provide bias voltages and otherwise drive thepower supply switches of power supply 50, specifically MOSFETs 235, 239,245, 269 and 279 (see FIGS. 3 a and 3 b).

More particularly, input 906 is a digital power enable signal thatcontrols the on or off status of MOSFETs 235, 239, 245, 269, 279. Input934 is Batt+, the power from the series connected string ofelectrochemical cells downstream of power supply 50. Input 932Charge_Supply, is the power from the i/o jack. Diodes 930 and 932effectively select whether Batt+power or Charge_Supply power is used inthe isolated power supply circuitry. Output 928 sends some of theelectrical power to the microprocessor as Control_Power (see FIG. 22 atinput 1171).

The electrical power from Batt+ 930 and/or Charge_Supply 936 istransformed into the six voltage levels by core/winding assemblies 922,940, 952, 977 and 1002. These five core/winding assemblies utilize coilsbuilt into the board (not shown) that physically supports the variouscomponents of power supply 50. All five coils are adjacent to a commoncore. As will be understood by those of skill in the art, theelectromagnetic interaction at the five core/winding assemblies, workingin conjunction with the other components of FIGS. 16-19, transforms thepower from Batt+ and/or Charge_Supply into the six voltage signalsrespectively at terminals 960, 966, 985, 991, 1010, 1016.

The core/winding assemblies of FIGS. 16 to 19 means that the six voltagesignals V1±, V2±, V3± are not necessarily referenced to the voltagelevel of the Batt+ and Charge_Supply power inputs. Rather: (1) V1±signals happen to be referenced to Charge_Supply (because Charge_Supplyis provided at input 962, not because of the use of Charge_Supply asinput power); (2) V2± signals are referenced to an AC high frequencyground; and (3) V3± signals happen to be referenced to Batt+ (becauseBatt+ is provided at input 962, not because of the use of Batt+ as inputpower). This carefully controlled reference voltage level for the sixvoltage signals is important because these six signals operate and biasMOSFETs 235, 239, 245, 269, 279. As will be understood by those of skillin the art upon a review of FIGS. 3 a and 3 b, each of the MOSFETs mustbe referenced to the appropriate level (Charge_Supply, high frequencyground, Batt+) regardless of whether the power supplied through isolatedpower supply circuitry 900, 950, 975, 1000 comes from Charge_Supply orfrom Batt+ at any given point of time.

In this exemplary embodiment of power supply 50, isolated power supplycircuitry 900, 950, 975, 1000 has a SEPIC configuration (see capacitor938 at FIG. 16). Alternatively, flyback or other configurations, nowknown or to be developed in the future, could be used in the isolatedpower supply circuitry, but SEPIC will often be the most energyefficient configuration.

The microcontroller circuitry 1025, 1100, 1125 of FIGS. 20 to 22 willnow be explained by first identifying the constituent components in eachof the Figs., followed by discussion of the operation of themicrocontroller circuitry and its role in switching power supply 50.Microcontroller circuitry first portion 1025 includes analog circuitryconnected to ports 1-3, 20-23, 25, 27 and 28 of 28-port microcontroller1027. Microcontroller circuitry second portion 1100 includes analogcircuitry connected to ports 24 and 26 of 28-port microcontroller 1027.Microcontroller circuitry third portion 1125 includes digital circuitryconnected to ports 4-19 of 28-port microcontroller 1027.

Referring to FIG. 20, microcontroller circuitry first portion 1025includes inputs 1029, 1031, 1053, 1055, 1069, 1079; ground (analog ordigital as appropriate) 1037, 1049, 1059, 1065, 1073; resistors 1033,1035, 1051, 1053, 1063, 1067, 1071, 1077; capacitors 1039, 1041, 1043,1045, 1047, 1057, 1061, 1075; and 28-port microcontroller 1027. Thecircuit elements of the microcontroller circuitry first portion areelectrically interconnected as shown in FIG. 20. Preferred electricalcharacteristics for some of the elements of microcontroller circuitryfirst portion 1025 are set forth in parentheses in the following list:input 1029 (IS+); input 1031 (Cell_1); input 1053 (Ireg_monitor); input1055 (IS+); input 1069 (Cell_3); input 1079 (Cell_2); resistor 1033(301K); resistor 1035 (301K); resistor 1051 (143K); resistor 1053(121R); resistor 1063 (143K); resistor 1067 (1M0); resistor 1071 (150K);resistor 1077 (453K); capacitor 1039 (1 μF); capacitor 1041 (1 μF);capacitor 1043 (1 μF); capacitor 1045(0.47 μF); capacitor 1047 (1 μF);capacitor 1057 (0.47 μF); capacitor 1061 (1 μF); capacitor 1075 (1 μF);microcontroller port 1 (RA1AN1); microcontroller port 2 (RA0/AN0);microcontroller port 3 (RD3/REFB); microcontroller port 20 (Vss);microcontroller port 21 (SUM); microcontroller port 22 (CDAC);microcontroller port 23 (RD7/AN7); microcontroller port 25 (RD5/AN5);microcontroller port 27 (RA3AN3); and microcontroller port 28 (RA2AN2).

Referring to FIG. 21, microcontroller circuitry second portion 1100includes inputs 1112, 1116; ground (preferably analog) 1115; resistors1106, 1108, 1110, 1114; capacitors 1102, 1104; and 28-portmicrocontroller 1027. The circuit elements of the microcontrollercircuitry second portion are electrically interconnected as shown inFIG. 21. Preferred electrical characteristics for some of the elementsof microcontroller circuitry second portion 1100 are set forth inparentheses in the following list: input 1112 (Charge_Supply); input1116 (Batt+); resistor 1106 (143K); resistor 1108 (143K); resistor 1110(1M0); resistor 1114 (1M0); capacitor 1102 (1 μF); capacitor 1104 (1μF); microcontroller port 24 (RD6/AN6); and microcontroller port 26(RD4/AN4).

Referring to FIG. 22, microcontroller circuitry third portion 1125includes inputs 1131, 1147, 1149, 1157, 1159, 1171, 1181; outputs 1127,1129, 1133, 1135, 1137, 1139, 1141, 1198, 1199; terminals 1155, 1165,1185; ground (analog or digital as appropriate) 1177, 1185, 1193;resistors 1143, 1145, 1151, 1153, 1161, 1163, 1169, 1173, 1179, 1189,1195, 1197; capacitors 1175, 1178, 1183; 28-port microcontroller 1027;component 1191; diode 1187; and component 1167. The circuit elements ofthe microcontroller circuitry third portion are electricallyinterconnected as shown in FIG. 22. Preferred electrical characteristicsfor some of the elements of microcontroller circuitry third portion 1125are set forth in parentheses in the following list: input 1131(Overcharge_monitor); input 1147 (SDAB); input 1149 (SCLB); input 1157(SDAA); input 1159 (SCLA); input 1171 (Control_Power); input 1181(Jack_Sense); output 1127 (Over_Current); output 1129 (Enable); output1133 (LED1); output 1135 (Power_Enable); output 1137 (Pass_Mode); output1139 (Charge_Discharge); output 1141 (Buck_Boost); output 1198 (SCLA);output 1199 (SDAA); terminal 1155 (+5.4V); terminal 1165 (+4.7V);terminal 1185 (+4.7V); resistor 1143 (121R); resistor 1145 (121R);resistor 1151 (100K); resistor 1153 (100K); resistor 1161 (100K);resistor 1163 (100K); resistor 1169 (121R); resistor 1173 (2M2);resistor 1179 (1M0); resistor 1189 (2K21); resistor 1195 (121R);resistor 1197 (121R); capacitor 1175 (0.1 μF); capacitor 1178 (0.1 μF);capacitor 1183 (0.01 μF); microcontroller 1027 port 4 (RD2/CMPB);microcontroller 1027 port 5 (RD1/SDAB); microcontroller 1027 port 6(RD0/SCLB); microcontroller 1027 port 7 (OSC2/CLKOUT); microcontroller1027 port 8 (OSC1/PBTN); microcontroller 1027 port 9 (VDD);microcontroller 1027 port 10 (VREG); microcontroller 1027 port 11(RC7/SDAA); microcontroller 1027 port 12 (RC6/SCLA); microcontroller1027 port 13 (RC5); microcontroller 1027 port 14 (MCLR/Vpp);microcontroller 1027 port 15 (RC4); microcontroller 1027 port 16(Power_Enable); microcontroller 1027 port 17 (Pass_Mode);microcontroller 1027 port 18 (RC1/CMPA); microcontroller 1027 port 19(RC0/REFA); diode 1187 (preferably model number BAV70); component 1167(model IRLML2502).

Now that the microcontroller circuitry 1025, 1100, 1125 has beenidentified, its functionality will be briefly discussed. Microcontrollerchip 1127 is preferably model PIC14000SS. Microcontroller 1027 controlsthe mode that the switching power supply operates in (e.g., buck charge,buck discharge, boost charge, boost discharge) and performs otherimportant control functions.

Oscillator circuitry 1200 of FIG. 23 will now be explained by firstidentifying the constituent components, followed by discussion of theoperation of the oscillator circuitry and its role in switching powersupply 50. Referring to FIG. 23, oscillator circuitry 1200 includesinputs 1206, 1208, 1232; output 1270; terminals 1204, 1214, 1226, 1242,1252, 1262; grounds (analog or digital as appropriate) 1210, 1216, 1228,1248, 1254, 1264; resistors 1218, 1222, 1230, 1234, 1238, 1240, 1244,1246, 1256, 1266, 1268; capacitors 1220, 1236, 1258; d-a converter 1202;operational amplifiers 1212, 1224, 1250; and comparator 1260. Thecircuit elements of the oscillator circuitry are electricallyinterconnected as shown in FIG. 23. Preferred electrical characteristicsfor some of the elements of oscillator circuitry 1200 are set forth inparentheses in the following list: input 1206 (SDAB); input 1208 (SCLB);input 1232 (Duty_Cycle_Control); output 1270 (osc_out); terminal 1204(+5.4V); terminal 1214 (+5.4V); terminal 1226 (+5.4V); terminal 1242(+5.4V); terminal 1252 (+5.4V); terminal 1262 (+5.4V); resistor 1218(1K0); resistor 1222 (1K0); resistor 1230 (18K2); resistor 1234 (39K2);resistor 1238 (121R); resistor 1240 (1K0); resistor 1244 (100K);resistor 1246 (100K); resistor 1256 (1K0); resistor 1266 (100K);resistor 1268 (698K); capacitor 1220 (100 pF); capacitor 1236 (100 pF);capacitor 1258 (22 pF); operational amplifier 1212 (model TC1034);operational amplifier 1224 (model LMV710 made by National Semiconductorof Santa Clara, Calif.); operational amplifier 1250 (model LMV710); andcomparator 1260 (model LMV7219 made by National Semiconductor).

Now that oscillator circuitry 1200 has been identified, itsfunctionality will be briefly discussed. Inputs SDAB, SCLB andDuty_Cycle_Control are input to the oscillator circuitry to produceoutput osc_out. Inputs SDAB, SCLB are I²C format inputs that represent avoltage from 0-5 volts that forms a control signal to the oscillator.Duty_Cycle_Control is an analog signal. The output osc out controls theoscillator.

Oscillator circuitry 1200 produces an oscillation signal that has avariable duty cycle, a variable frequency and no fixed on-time oroff-time for a duty cycle. This is different than conventionaloscillators because conventional oscillators generally have at least oneof the following restrictions: fixed frequency, fixed on time and/orfixed off time. By utilizing oscillator circuitry that can produce anoscillation signal having both a fixed frequency and no fixed on or offtime, the multiple modes of operation (e.g., charge buck, charge boost,discharge buck, discharge boost) are greatly facilitated. For example,because there are no on or off time restrictions, duty cycles rangingfrom 0% to 100% are possible. This robust range of possible duty cycleshelps make it possible to operate more efficiently and/or to achievemany different modes of operation. In exemplary oscillator circuitry1200, the frequency range is dc operation up to a maximum of about 500kHz. FIG. 42 is a graph, showing a generally parabola shapedrelationship, of frequency versus duty cycle for oscillator circuitry1200.

As shown in FIG. 24, capacitor set circuitry 1275 includes terminal1277, six (6) parallel-connected capacitors 1281 and (preferably analog)ground 1279. Terminal 1277 is preferably at +5.4V. The 6parallel-connected capacitors preferably each have a value of 0.1 μF.Capacitor set 1275 provides capacitance across selected portion(s) ofoscillator circuitry 1200.

Overcharge protection circuitry 1300, 1350 of FIGS. 25 and 26 will nowbe explained by first identifying the constituent components in each ofthe Figs., followed by discussion of the operation of the overchargeprotection circuitry and its role in switching power supply 50.Referring to FIG. 25, overcharge protection circuitry first portion 1300includes inputs 1304, 1306, 1310, 1314; resistors 1304, 1308, 1312,1316; capacitors 1318, 1320, 1322, 1324; (preferably digital) ground1326; and 8-port overvoltage protection chip 1302. The circuit elementsof the overcharge protection circuitry first portion are electricallyinterconnected as shown in FIG. 25. Preferred electrical characteristicsfor some of the elements of overcharge protection circuitry firstportion 1300 are set forth in parentheses in the following list: input1304 (Cell_1); input 1306 (Cell_2); input 1310 (Cell_3); input 1314(Batt+); resistor 1304 (1K0); resistor 1308 (1K0); resistor 1312 (1K0);resistor 1316 (1K0); capacitor 1318 (0.1 μF); capacitor 1320 (0.1 μF);capacitor 1322 (0.1 μF); capacitor 1324 (0.1 μF); overvoltage protectionchip 1302 port 2 (SENSE); overvoltage protection chip 1302 port 3 (VC1);overvoltage protection chip 1302 port 4 (VC2); overvoltage protectionchip 1302 port 5 (VC3); overvoltage protection chip 1302 port 6 (VSS).

Referring to FIG. 26, overcharge protection circuitry second portion1350 includes input 1352; outputs 1366, 1368; resistor 1354; capacitors1356, 1358; (preferably digital) grounds 1351, 1360; overvoltageprotection chip 1302; and FETs 1362, 1364. The circuit elements of theovercharge protection circuitry second portion are electricallyinterconnected as shown in FIG. 26. Preferred electrical characteristicsfor some of the elements of overcharge protection circuitry secondportion 1350 are set forth in parentheses in the following list: input1352 (Batt+); output 1366 (Overcharge); output 1368(Overcharge_monitor); resistor 1354 (121R); capacitor 1356 (0.1 μF);capacitor 1358 (0.1 μF); FET 1362 (model IRF7509 made by InternationalRectifier); FET 1364 (model IRF7509); overvoltage protection chip 1302port 1 (VCC); overvoltage protection chip 1302 port 7 (ICT); overvoltageprotection chip 1302 port 8 (CO).

Now that overcharge protection circuitry 1300, 1350 has been identified,its functionality will be briefly discussed. It is conventional to use apre-programmed overvoltage protection chip in conjunction with switchingpower supplies used for charging electrochemical cells. This redundantcircuitry is warranted in this application because electrochemical cellscan be damaged by overvoltage conditions and because overvoltageconditions may be: highly specific to electrochemical cell type and/orinvolve complex numerical or logical relationships. More particularly,overvoltage 1302 is preferably model S-8244AAHFN-CEH-T2 made by Seiko.The Overcharge signal output by overcharge protection circuitryoverrides any inconsistent signals being put out by the microprocessorin its normal control of operation of the switching power supply. TheOvercharge_monitor signal output by overcharge protection circuitrycommunicates to the microprocessor that the overriding Overcharge outputsignal is in effect.

Programmable logic circuitry 1400, 1450, 1500, 1550, 1600, 1625, 1650,1675, 1700, 1710, 1720, 1730 of FIGS. 27 through 38 will now beexplained by first identifying the constituent components in each of theFigs., followed by discussion of the operation of the programmable logiccircuitry and its role in switching power supply 50. Programmable logiccircuitry first through fourth portions 1400, 1450, 1500, 1550, as shownin FIGS. 27 through 30, include circuitry connected to programmablelogic chip 1402 (preferably model number LC4032ZC made by LatticeSemiconductor).

Referring to FIG. 27, programmable logic circuitry first portion 1400includes terminals 1410, 1418; resistor 1414; capacitors 1408, 1426;(preferably digital) grounds 1406, 1416, 1424; programmable logic chip1402; and test points 1404, 1412, 1420, 1422. The circuit elements ofthe programmable logic circuitry first portion are electricallyinterconnected as shown in FIG. 27. Preferred electrical characteristicsfor some of the elements of programmable logic circuitry first portion1400 are set forth in parentheses in the following list: terminal 1410(+3.3V); terminal 1418 (+1.8V); resistor 1414 (4K75); capacitor 1408(0.1 μF); capacitor 1426 (0.1 μF); programmable logic chip 1402 port 1(TD1); programmable logic chip 1402 port 2 (A5); programmable logic chip1402 port 3 (A6); programmable logic chip 1402 port 4 (A7); programmablelogic chip 1402 port 5 (GND (Bank0)); programmable logic chip 1402 port6 (VCC(Bank0)); programmable logic chip 1402 port 7 (A8); programmablelogic chip 1402 port 8 (A9); programmable logic chip 1402 port 9 (A10);programmable logic chip 1402 port 10 (A11); programmable logic chip 1402port 11 (TCK); programmable logic chip 1402 port 12 (VC0); andprogrammable logic chip 1402 port 13 (GND).

Referring to FIG. 28, programmable logic circuitry second portion 1450includes inputs 1452, 1454, 1456, 1458, 1460, 1462, 1464; andprogrammable logic chip 1402. The circuit elements of the programmablelogic circuitry second portion are electrically interconnected as shownin FIG. 28. Preferred electrical characteristics for some of theelements of programmable logic circuitry first portion 1400 are setforth in parentheses in the following list: input 1452 (Enable); input1454 (Predictor_Output); input 1456 (seriesa); input 1458 (shunta);input 1460 (Pass_Mode); output 1462 (Node_Control); input 1464(Charge_Discharge); programmable logic chip 1402 port 14 (A12);programmable logic chip 1402 port 15 (A13); programmable logic chip 1402port 16 (A14); programmable logic chip 1402 port 17 (A15); programmablelogic chip 1402 port 18 (CLK1/I); programmable logic chip 1402 port 19(CLK2/I); programmable logic chip 1402 port 20 (B0); programmable logicchip 1402 port 21 (B1); programmable logic chip 1402 port 22 (B2);programmable logic chip 1402 port 23 (B3); programmable logic chip 1402port 24 (B4).

Referring to FIG. 29, programmable logic circuitry third portion 1500includes input 1506; terminals 1501, 1503, 1512; resistor 1502;capacitors 1508, 1516; (preferably digital) grounds 1510, 1518;programmable logic chip 1402; and test points 1504, 1514. The circuitelements of the programmable logic circuitry first portion areelectrically interconnected as shown in FIG. 29. Preferred electricalcharacteristics for some of the elements of programmable logic circuitrythird portion 1500 are set forth in parentheses in the following list:input 1506 (oc_signal); terminal 1501 (+1.8V); terminal 1503 (+1.8V);terminal 1512 (+3.3V); resistor 1502 (4K75); capacitor 1508 (0.1 μF);capacitor 1516 (0.1 μF); programmable logic chip 1402 port 25 (TMS);programmable logic chip 1402 port 26 (B5); programmable logic chip 1402port 27 (B6); programmable logic chip 1402 port 28 (B7); programmablelogic chip 1402 port 29 (GND(Bank1)); programmable logic chip 1402 port30 (VCCO(Bank1)); programmable logic chip 1402 port 31 (B8);programmable logic chip 1402 port 32 (B9); programmable logic chip 1402port 33 (B10); programmable logic chip 1402 port 34 (B11); programmablelogic chip 1402 port 35 (TD0); programmable logic chip 1402 port 36(VCC); and programmable logic chip 1402 port 37 (GND).

Referring to FIG. 30, programmable logic circuitry fourth portion 1550includes inputs 1552, 1554, 1558, 1560; output 1556; terminal 1576;resistors 1562, 1564, 1572; capacitors 1565, 1566, 1574; (preferablydigital) grounds 1568, 1580; programmable logic chip 1402; inverter1570; and inverter 1578. The circuit elements of the programmable logiccircuitry fourth portion are electrically interconnected as shown inFIG. 30. Preferred electrical characteristics for some of the elementsof programmable logic circuitry fourth portion 1550 are set forth inparentheses in the following list: input 1552 (Buck_Boost); input 1554(seriesb); input 1558 (shuntb); input 1560 (osc_out); output 1556(Integrator_Reset); terminal 1576 (+5.4V); resistor 1562 (10R0);resistor 1564 (499R); resistor 1572 (499R); capacitor 1565 (100 pF);capacitor 1566 (100 pF); capacitor 1574 (100 pF); inverter 1570 (model74VHCT14PW); and inverter 1578 (model 74VHCT14PW); programmable logicchip 1402 port 38 (B12); programmable logic chip 1402 port 39 (B13);programmable logic chip 1402 port 40 (B14); programmable logic chip 1402port 41 (B15/GOE1); programmable logic chip 1402 port 42 (CLK3/I);programmable logic chip 1402 port 43 (CLK0/I); programmable logic chip1402 port 44 (A0/GOE0); programmable logic chip 1402 port 45 (A1);programmable logic chip 1402 port 46 (A2); programmable logic chip 1402port 47 (A3); and programmable logic chip 1402 port 48 (A4).

Inverters 1570, 1578 and their associated resistor-capacitor networkpreferably condition the waveform of the osc_out input signal, as wellas providing some phase shifting. One reason for the phase shifting isto help avoid shoot-through. Shoot-through happens when small overlapsbetween turning the various FETS on and off occur. These shoot-throughoverlaps cause transient, inefficient power transfers in the passivecircuitry of the switching power supply. Therefore, by preventingshoot-through by phase shifting, the switching power supply is improvedin efficiency.

Referring to FIG. 31, programmable logic circuitry fifth portion 1600includes terminals 1604, 1614; capacitors 1606, 1610, 1612; (preferablydigital) ground 1608; and voltage regulator 1602 (preferably modelnumber LT1761-3.3 made by Linear Technology). The circuit elements ofthe programmable logic circuitry fifth portion are electricallyinterconnected as shown in FIG. 31. Preferred electrical characteristicsfor some of the elements of programmable logic circuitry fifth portion1600 are set forth in parentheses in the following list: terminal 1604(+5.4V); terminal 1614 (+3.3V); capacitor 1606 (1 μF); capacitor 1610(0.01 μF); capacitor 1612 (1 μF); voltage regulator 1602 port 1 (VIN);voltage regulator 1602 port 2 (GND); voltage regulator 1602 port 3(SHDN); voltage regulator 1602 port 4 (BYP); and voltage regulator 1602port 5 (VOUT).

Referring to FIG. 32, programmable logic circuitry sixth portion 1625includes terminals 1629, 1639; capacitors 1631, 1635, 1637; (preferablydigital) ground 1633; and voltage regulator 1627 (preferably modelnumber LT1761-1.8 made by Linear Technology). The circuit elements ofthe programmable logic circuitry sixth portion are electricallyinterconnected as shown in FIG. 32. Preferred electrical characteristicsfor some of the elements of programmable logic circuitry fifth portion1600 are set forth in parentheses in the following list: terminal 1629(+5.4V); terminal 1639 (+1.8V); capacitor 1631 (1 μF); capacitor 1635(0.01 μF); capacitor 1637 (1 μF); voltage regulator 1627 port 1 (VIN);voltage regulator 1627 port 2 (GND); voltage regulator 1627 port 3(SHDN); voltage regulator 1627 port 4 (BYP); and voltage regulator 1627port 5 (VOUT). Voltage regulators 1602, 1627 respectively provide the+3.3V (terminal 1614) and +1.8V (terminal 1639) required by the lowpower microcontroller.

Referring to FIG. 33, programmable logic circuitry sixth portion 1650includes +5.4V terminal 1652; 0.1 μF capacitor 1654; and (preferablydigital) ground 1656. Programmable logic sixth portion providescapacitance across selected portion(s) of the programmable logiccircuitry.

Referring to FIG. 34, programmable logic circuitry eighth portion 1675includes input 1685; output 1693; terminal 1677; capacitor 1689;(preferably digital) ground 1687; resistors 1681, 1691; and FETs 1679,1683. The circuit elements of the programmable logic circuitry eighthportion are electrically interconnected as shown in FIG. 34. Preferredelectrical characteristics for some of the elements of programmablelogic circuitry eighth portion 1675 are set forth in parentheses in thefollowing list: input 1685 (Over_Current); output 1693 (oc_signal);terminal 1677 (+5.4V); capacitor 1689 (0.01 μF); resistor 1681 (221K);resistor 1691 (10K0); and FET 1679 (model IRF7509 made by InternationalRectifier); and FET 1683 (model IRF7509).

Referring to FIG. 35, programmable logic circuitry ninth portion 1700includes input 1702 (shunta); inverter 1704 (preferably model74VHCT14PW); and output 1706 (Shunta_In). Referring to FIG. 36,programmable logic circuitry tenth portion 1710 includes input 1712(seriesa); inverter 1714 (preferably model 74VHCT14PW); and output 1716(Seriesa_In). Referring to FIG. 37, programmable logic circuitryeleventh portion 1720 includes input 1722 (shuntb); inverter 1724(preferably model 74VHCT14PW); and output 1726 (Shuntb_In). Referring toFIG. 38, programmable logic circuitry twelfth portion 1730 includesinput 1732 (seriesb); inverter 1734 (preferably model 74VHCT14PW); andoutput 1736 (Seriesb_In). Inverters 1704, 1714, 1724, 1734 act asinverters and buffers with respect to their respective signals.Programmable logic circuitry ninth to twelfth portions 1700, 1710, 1720,1730 impart sharp rising edges on the output signals. To explain, theinput signals come from the microprocessor, which is a low power devicethat consequently cannot impart sharp rising edges. So, the rising edgesare sharpened by circuitry 1710, 1720, 1730, 1700 so that the outputsignals (Shunta_In, Seriesa_In, Shuntb_In, Seriesb_In) can be accuratelyprocessed by the amplifier.

Now that the twelve portions of the programmable logic circuitry havebeen identified, its functionality will be briefly discussed.Programmable logic chip 1402 is preferably a multiple times programmablelogic chip. Preferably, the programmable logic chip is programmable onlyby a lab technician and not: (1) easily reprogrammable by anend-consumer; and/or (2) programmable by circuitry in the switchingpower supply (e.g., microcontroller). The above-mentioned test pointsare utilized in this technician programming process.

The programmable logic chip organizes the inventive multiple modeoperation of the switching power supply. Specifically, the programmablelogic chip stores multiple variable truth tables, with input variablescorresponding to mode of operation and other operating conditions asappropriate. Alternatively, this organization of the modes could beaccomplished in the microcontroller. However, by using a separate,dedicated programmable logic chip, the organizational functionality canbe handled much more quickly, which is especially important in thecontext of a high efficiency switching power supply. As a furtheralternative, this organization of the modes could be accomplished bydiscrete logic components. However, by using a separate, dedicatedprogrammable logic chip, the organizational functionality can be handledin less space and with less complexity of hardware.

Zero current predictor circuitry 1750 of FIG. 39 will now be explainedby first identifying the constituent components, followed by discussionof the operation of the zero current predictor circuitry and its role inswitching power supply 50. Referring to FIG. 39, zero current predictorcircuitry 1750 includes inputs 1754, 1762, 1764, 1765, 1768, 1796;output 1789; terminals 1758, 1770, 1774, 1788, 1798; resistors 1780,1782; capacitors 1778, 1784; (preferably analog) grounds 1756, 1769,1776, 1790, 1794; analog switches 1760, 1766, 1792; and comparators1772, 1786. The circuit elements of the zero current predictor circuitryare electrically interconnected as shown in FIG. 39. Preferredelectrical characteristics for some of the elements of zero currentpredictor circuitry 1750 are set forth in parentheses in the followinglist: input 1754 (Node_Control); input 1762 (Node_A_Signal); input 1764(Node_B_Signal); input 1765 (Node_A_Signal); input 1768 (Node_Control);input 1796 (Integrator_Reset); output 1789 (Predictor_Output); terminal1758 (5.4V); terminal 1770 (5.4V); terminal 1774 (5.4V); terminal 1788(5.4V); terminal 1798 (5.4V); resistor 1780 (121R); resistor 1782(121R); capacitor 1778 (220 pF); capacitor 1784 (10 pF); switch 1760port 1 (Select); switch 1760 port 2 (V+); switch 1760 port 3 (GND);switch 1760 port 4 (NO); switch 1760 port 5 (COM); switch 1760 port 6(NC); switch 1766 port 1 (Select); switch 1766 port 2 (V+); switch 1766port 3 (GND); switch 1766 port 4 (NO); switch 1766 port 5 (COM); switch1766 port 6 (NC); comparator 1772 (model LMV710); comparator 1786 (modelLMV7219); and switch 1792 port 1 (COM); switch 1792 port 2 (NO); switch1792 port 3 (GND); switch 1792 port 4 (ENABLE); switch 1792 port 5 (V+);switch 1760 (model NLAS4599 made by ON Semiconductor); switch 1766(model NLAS4599); and 1792 (model NLAS4501 made by ON Semiconductor).

Now that zero current predictor circuitry 1750 has been identified, itsfunctionality will be briefly discussed. Because power supply 50 usesMOSFET power supply switches to form current path(s) between an inductorand a capacitor (see FIG. 3 b at reference numerals 253, 255, 269, 279,273), and because the supply is sometimes operated in synchronousoperation, it is critical to make sure that the inductor current doesnot get down to zero because that could lead to the bad inefficiency ofreverse current, wherein the inductor pulls charge from the outputcapacitor. Therefore, special care is taken to make sure that the MOSFETis closed art least slightly before inductor current reaches zero.

This special care takes the form of zero current predictor circuitry1750. Zero current predictor circuitry uses the voltage across theinductor (see FIG. 3 b at reference numerals 253, 255) to control aconstant current through capacitor 1778. The capacitor voltage levelproportionally mirrors the inductor current. This is because rate ofchange in current in an inductor as a function of voltage isproportional to the rate of change in the voltage of a capacitor at agiven current level. So, capacitor 1778 voltage proportionally mimicsthe inductor current level, as inductor current varies over time.

Zero current predictor detects the rate of change in capacitor 1778voltage. Comparator 1772 and associated circuitry acts as an integratorthat continually integrates the detected rate of change in voltage todetermine the capacitor voltage at any given point in time of operation.If determined capacitor voltage gets too close to zero, then it iseffectively predicted that inductor current will reach zero. Therefore,when the integrated capacitor voltage falls below a minimum thresholdlevel, comparator 1786 outputs the Predictor_Output signal to turn offthe associated power supply switch before inductor current has anopportunity to reach zero. Analog switch 1792 resets, or shorts,capacitor 1778 when the Predictor_Output signal indicates a zero currentprediction. This prevents cumulative integration of measurement errors.

The zero current predictor is utilized to prevent reverse current flow.The current predictor works by sensing the voltage across an inductorand/or the rate of change of voltage across an inductor. This zerocurrent predictor is believed to be especially advantageous insynchronous switching power supplies. This zero current prediction isdifferent than power supply control methods for measuring the current inthe inductor for the express for purpose of limiting the current peaksto prevent inductor saturation and FET damage, and to provide currentregulation without the use of a current shunt. This is done in variousmanners all with the intent of knowing what the current is at a specificpoint in time. The zero current prediction approach is quite differentin that respect. The zero current prediction approach does notnecessarily make any effort to realize the absolute value of current.Rather, the zero current prediction method predicts when the currentmight be zero, for the purpose of improving efficiency. This isdifferent than conventional devices that make efforts to actuallymeasure the current, for both peak current control and reverse currentprevention (occurs after current reaches zero.) One of the basicproblems with this approach is, of course, it is very difficult tomeasure very small currents. The present invention avoids that by notmeasuring actual current but by “predicting when it “might” be zero. Theapproach has resulted in some significant improvements in efficacy. Thiskind of zero current predictor can prevent inductor from getting down tozero current as synchronous FETs are switching on and off. The rate ofchange of current in an inductor can be mimicked by the rate of changeof voltage in a capacitor, which is the preferred way of performing zerocurrent prediction according to the present invention.

FIG. 40 shows decoupling capacitor set 1800, for use in the presentinvention, including +5.4 V terminal 1802, ground 1806; and sixcapacitors connected in parallel 1804. Of the six parallel-connectedcapacitors, five are preferably 0.1 μF and the remaining capacitor ispreferably 1 μF. The use of both 0.1 μF and 1 μF capacitors causesdecoupling at both high and low frequencies.

Many variations on the above-described embodiments of this invention arepossible. The fact that a product or process exhibits differences fromone or more of the above-described exemplary embodiments does not meanthat the product or process is outside the scope (literal scope and/orother legally-recognized scope) of the following claims.

DEFINITIONS

The following definitions are provided to facilitate claiminterpretation and claim construction:

Present invention: means at least some embodiments of the presentinvention; references to various feature(s) of the “present invention”throughout this document do not mean that all claimed embodiments ormethods include the referenced feature(s).

First, second, third, etc. (“ordinals”): Unless otherwise noted,ordinals only serve to distinguish or identify (e.g., various members ofa group); the mere use of ordinals implies neither a consecutivenumerical limit nor a serial limitation.

Power signal: any electrical power flow caused primarily for the purposeof transferring electrical power, regardless of whether the “signal”includes any informational component (generally it will not) andregardless of whether some or all of the power is not transferred (forexample, in some embodiments, some of the power will be used to run theswitching power supply and therefore there will be some power from thepower signal that is not transferred in these embodiments, even thoughelectrical power transfer is still the primary purpose of the powersignal.

To the extent that the definitions provided above are consistent withordinary, plain, and accustomed meanings (as generally shown bydocuments such as dictionaries and/or technical lexicons), the abovedefinitions shall be considered controlling and supplemental in nature.To the extent that the definitions provided above are inconsistent withordinary, plain, and accustomed meanings (as generally shown bydocuments such as dictionaries and/or technical lexicons), the abovedefinitions shall control. If the definitions provided above are broaderthan the ordinary, plain, and accustomed meanings in some aspect, thenthe above definitions shall be considered to broaden the claimaccordingly.

To the extent that a patentee may act as its own lexicographer underapplicable law, it is hereby further directed that all words appearingin the claims section, except for the above-defined words, shall take ontheir ordinary, plain, and accustomed meanings (as generally shown bydocuments such as dictionaries and/or technical lexicons), and shall notbe considered to be specially defined in this specification.Notwithstanding this limitation on the inference of “specialdefinitions,” the specification may be used to evidence the appropriateordinary, plain and accustomed meanings (as generally shown bydictionaries and/or technical lexicons), in the situation where a wordor term used in the claims has more than one alternative ordinary, plainand accustomed meaning and the specification is actually helpful inchoosing between the alternatives.

1. A switching power supply comprising: at least one power signal inputstructured as circuitry for providing an input electrical power signalto the switching power supply; at least one power signal outputstructured as circuitry for providing an output electrical power signalfrom the switching power supply; a passive component set comprising atleast one inductor and a capacitor; an active component set comprising afirst power supply switch connected in series between the inductor andcapacitor; and zero current predictor circuitry structured andelectrically connected to predict when inductor current will fall tozero and to send a signal to close the first power supply switch basedon this prediction.
 2. A switching power supply comprising: at least onepower signal input structured as circuitry for providing an inputelectrical power signal to the switching power supply; at least onepower signal output structured as circuitry for providing an outputelectrical power signal from the switching power supply; a passivecomponent set comprising at least one inductor and a capacitor; anactive component set comprising a first power supply switch connected inseries between the inductor and capacitor; and zero current predictorcircuitry structured and electrically connected to predict when inductorcurrent will fall to zero and to send a signal to close the first powersupply switch based on this prediction, wherein the zero currentpredictor circuitry comprises a zcp capacitor electrically connected andcontrolled based on the voltage across the inductor so that the zcpcapacitor's voltage proportionally mirrors the inductor current.
 3. Thesupply of claim 2 wherein the zero current predictor further comprises areset circuit structured and electrically connect to short the zcpcapacitor after a zero current prediction is made.
 4. A switching powersupply comprising: at least one power signal input structured ascircuitry for providing an input electrical power signal to theswitching power supply; at least one power signal output structured ascircuitry for providing an output electrical power signal from theswitching power supply; a passive component set comprising at least oneinductor and a capacitor; an active component set comprising a firstpower supply switch connected in series between the inductor andcapacitor; and zero current predictor circuitry structured andelectrically connected to predict when inductor current will fall tozero and to send a signal to close the first power supply switch basedon this prediction, wherein the zero current predictor circuitrycomprises: a zcp capacitor electrically connected and controlled basedon the voltage across the inductor so that the zcp capacitor's voltageproportionally mirrors the inductor current; a zcp integrator isstructured and electrically connected to integrate the rate of change ofzcp capacitor voltage to determine zcp capacitor voltage; and a zcpcomparator is structured to indicate in an output signal the conditionthat the zcp voltage determined by the integrator has fallen below aminimum threshold.